Following an application from DSM Nutritional Products and Kemin Foods, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of France, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to a combination of lutein and zeaxanthin and improved vision under bright light conditions.
The scope of the application was proposed to fall under a health claim based on newly developed scientific evidence. The application included a request for the protection of proprietary data.
The food that is the subject of the health claim is a combination of lutein and zeaxanthin. Lutein and zeaxanthin are xanthophyll carotenoids naturally present in food, especially in green leafy vegetables. Lutein and zeaxanthin can be measured in foods by established methods. The Panel considers that the food, a combination of lutein and zeaxanthin, which is the subject of the health claim is sufficiently characterised.
The claimed effect relates to improved visual performance, in particular under bright light conditions. The target population proposed by the applicant is the general healthy population. The Panel considers that improved vision under bright light conditions is a beneficial physiological effect.
The applicant provided a total of 10 published and one unpublished human intervention studies as being pertinent to the health claim.
Five studies investigated the effects of lutein and/or zeaxanthin on macular pigment optical density, but did not assess vision, whereas two studies investigated the effects of lutein only, and not of the combination of lutein plus zeaxanthin that is the subject of the health claim, on visual outcomes. The Panel considers that no conclusions can be drawn from these studies for the scientific substantiation of the claim.
Three published and one unpublished human intervention studies investigated the effects of lutein, either alone or in combination with zeaxanthin, on measures of vision. Two of these studies were already evaluated by the Panel in relation to a claim on lutein and maintenance of normal vision. The Panel considered that no conclusions could be drawn from these two studies for the scientific substantiation of the claim owing to important methodological limitations.
In a randomised, single-blind, placebo-controlled, parallel study, 36 subjects were randomly assigned to consume daily for six months (i) 20 mg lutein and 2 mg zeaxanthin, (ii) 10 mg lutein, 2 mg zeaxanthin and 10 mg meso-zeaxanthin, or (iii) a placebo. The outcome measures included visual acuity, contrast sensitivity, glare disability and photostress recovery. No significant differences were observed between the lutein plus zeaxanthin group and the placebo group for any measure of vision. The Panel notes the small sample size of the study and considers that no conclusions can be drawn from this study for the scientific substantiation of the claim.
In a randomised, double-blind, placebo-controlled, parallel trial, 115 subjects were randomised to consume daily for one year 10 mg lutein plus 2 mg zeaxanthin or a placebo. The primary outcome of the study, on which power calculations were based, was changes in macular pigment optical density. Secondary outcomes included measures of visual function, i.e. contrast sensitivity, glare sensitivity/tolerance and photostress recovery time. According to the statistical analysis plan, a repeated measures analysis of variance was foreseen to analyse the data. However, during a blind data review, the authors decided that a linear mixed model regression was more appropriate, owing to a “substantial number of unbalanced missing values”. In total, 34 subjects dropped out of the study. In the statistical analysis, the following three study populations were considered: (i) the “baseline set” (intention to treat, ITT); (ii) “intention to treat” (modified intention to treat, mITT); (iii) “protocol compliant” (per protocol, PP). When the ITT and mITT populations were considered, a significant improvement in contrast sensitivity and photostress recovery was reported in the lutein plus zeaxanthin group compared with the placebo group, whereas no significant changes between groups were observed for glare sensitivity. No significant differences were observed between groups for contrast sensitivity, photostress recovery or glare sensitivity when the analysis was performed in the PP population. The Panel notes that a combination of lutein and zeaxanthin had no effect on any outcomes of visual function in the population of subjects completing the protocol as planned (i.e. PP population), that at least 50 % of the subjects considered for the ITT and the mITT analyses had missing data owing to drop-out/non-compliance of study subjects, and that no evidence was provided that could justify the discrepancy of the results obtained from the different analyses. The Panel also notes that the statistical analysis was not carried out according to the statistical analysis plan, that measures of visual function were secondary outcomes in this study and that multiplicity of outcomes was not considered in the statistical analyses. The Panel considers that this study does not show an effect of a combination of lutein and zeaxanthin on vision.
In weighing the evidence, the Panel took into account that the one study from which conclusions could be drawn did not show an effect of lutein plus zeaxanthin on vision.
The Panel concludes that a cause and effect relationship has not been established between the consumption of a combination of lutein and zeaxanthin and improved vision under bright light conditions.